命令
\usepackage[english,greek]{babel}
使 MikTeX 2.9 永遠運作。
作業系統 Windows 7
輸出是
This is pdfTeX, Version 3.1415926-2.4-1.40.13 (MiKTeX 2.9)
entering extended mode
(C:/Users/x/AppData/Local/Temp/lyx_tmpdir.Hp3100/lyx_tmpbuf2/negreponti-1.tex
LaTeX2e <2011/06/27>
Babel <v3.8m> and hyphenation patterns for english, afrikaans, ancientgreek, ar
abic, armenian, assamese, basque, bengali, bokmal, bulgarian, catalan, coptic,
croatian, czech, danish, dutch, esperanto, estonian, farsi, finnish, french, ga
lician, german, greek, gujarati, hindi, hungarian, icelandic, indonesian, inter
lingua, irish, italian, kannada, kurmanji, latin, latvian, lithuanian, malayala
m, marathi, mongolian, mongolianlmc, monogreek, ngerman, nynorsk, oriya, panjab
i, pinyin, polish, portuguese, romanian, russian, sanskrit, serbian, slovak, sl
ovenian, spanish, swedish, swissgerman, tamil, telugu, turkish, turkmen, ukengl
ish, ukrainian, uppersorbian, usenglishmax, welsh, loaded.
編輯：來自OP的評論，小碼：
\makeatletter \makeatother
\documentclass[11pt,oneside]{amsart}
\usepackage[iso-8859-7]{inputenc}
\usepackage[a4paper]{geometry}
\usepackage{amsthm}
\usepackage{amstext}
\usepackage{amssymb}
\makeatletter
\usepackage[english,greek]{babel}
%\usepackage[default]{gfsneohellenic}
%\usepackage[LGR,T1]{fontenc} %% LGR encoding is needed for gfsneohellenic
\makeatother
\begin{document} klkk \greektext γφγγ
\end{document}